A new study by ocean conservation group Oceana has shown that one-third of the seafood sold in the U.S. could be mislabeled. Many of the mislabeled sea food products were a different type of fish than what was put on the label.

“The kind of mislabeling we’re talking about in this study is substituting one species of fish for the type that you ordered.” said Kimberly Warner, author of the report and a senior scientist at Oceana. “Say you ordered red snapper but you got a different type of snapper, or even another completely different species such as tilapia or rockfish.”

The study looked at 1,215 seafood samples from 674 different retail locations in 21 different states during the years 2010 to 2012. Of those samples, around 33% would be considered mislabeled by us. Food and Drug Administration (FDA) guidelines. Over 50% of the seafood tested from Southern California was found to be mislabeled.

Seafood samples labeled as snapper and tuna were the most likely types to be mislabeled. Of the 120 samples of snapper tested, 113 of them (87%) were found to be another type of fish.

In light of their findings, Oceana has called for a transparent national tracking system for seafood that tracks fish from boats all the way to consumers. It has also called on federal and state governments to ramp up inspections and enforcement of labeling violations.